A major factor in the propagation of an infectious disease is host genetics. In this study, 180 dairy cows (90 of each breed: Holstein and Montbéliarde) were used. Each breed's tested dairy cows were divided into two groups of comparable size (45 cows each), mastitis-free and mastitis-affected groups. Each cow's jugular vein was punctured to obtain blood samples for DNA and RNA extraction. In the examined Holstein and Montbéliarde dairy cows, single nucleotide polymorphisms (SNPs) related with mastitis resistance/susceptibility were found in the RASGRP1, NFkB, CHL1, MARCH3, PDGFD, MAST3, EPS15L1, C1QTNF3, CD46, COX18, NEURL1, PPIE, and PTX3 genes. Chi-square analysis of identified SNPs revealed a significant difference in gene frequency between mastitic and healthy cows. Except for CHL1, mastitic dairy cows of two breeds had considerably higher mRNA levels of the examined genes than did healthy ones. Marker-assisted selection and monitoring of dairy cows' susceptibility to mastitis may be accomplished through the use of discovered SNPs and changes in the gene expression profile of the studied genes. These findings also point to a possible method for reducing mastitis in dairy cows through selective breeding of animals using genetic markers linked to an animal's ability to resist infection.
Keywords: Holstein; Montbéliarde; candidate gene; gene expression; mastitis.